“Alternating hot and cold works better than either one alone.”

The research found this

Most of the evidence on contrast comes from sports recovery. A 2013 meta-analysis pooled 18 trials with 356 healthy participants who alternated hot water at 35.5–45°C with cold water at 8–15°C within an hour of hard exercise.1Source 1 · Meta-analysisContrast Water Therapy and Exercise Induced Muscle Damage: A Systematic Review and Meta-AnalysisBieuzen F, Bleakley CM, Costello JT. PLoS ONE, 2013.Read the paper ↗PubMed ↗ Compared with passive rest, contrast lowered muscle soreness at every time point the review examined, and strength loss was smaller.

Against other methods it held no clear edge. The same review found little evidence that contrast beat cold water immersion or any other active recovery method.1Source 1 · Meta-analysisContrast Water Therapy and Exercise Induced Muscle Damage: A Systematic Review and Meta-AnalysisBieuzen F, Bleakley CM, Costello JT. PLoS ONE, 2013.Read the paper ↗PubMed ↗ A Cochrane review found no difference in soreness between cold water and contrast immersion, and a 2023 meta-analysis found cold water alone beat contrast for most recovery outcomes.2Source 2 · Systematic reviewCold-water immersion (cryotherapy) for preventing and treating muscle soreness after exerciseBleakley C, McDonough S, Gardner E, et al.. Cochrane Database of Systematic Reviews, 2012.Read the paper ↗PubMed ↗3Source 3 · Meta-analysisEffects of Cold-Water Immersion Compared with Other Recovery Modalities on Athletic Performance Following Acute Strenuous Exercise in Physically Active Participants: A Systematic Review, Meta-Analysis, and Meta-RegressionMoore E, Fuller JT, Bellenger CR, et al.. Sports Medicine, 2023.Read the paper ↗PubMed ↗

A cold dip changes how a sauna session feels. In a 2026 crossover trial at a public lakeside sauna in Wales, 16 adults did two 15-minute rounds at 84.5°C on two separate days. On one day each break began with 90 seconds up to the neck in 19.9°C lake water.4Source 4 · Crossover trialThermal and cardiovascular responses to sauna are attenuated by adding cold water immersion to cooling breaksOwen TF, Giles CJ, Leaney SF, et al.. Experimental Physiology, 2026.Read the paper ↗PubMed ↗ By the end of the second round, core temperature was 37.55°C with the dips and 38.03°C without, and heart rate was 108 beats a minute against 125. People also rated the second round as easier to tolerate, and sweat loss didn't differ significantly. Follow that session minute by minute.

Alternating extremes also asks more of the heart. In nine winter swimmers, alternating sauna and ice water put the most intensive strain on the heart of the conditions tested, and adrenaline nearly doubled only in that condition.5Source 5 · Clinical trialSauna, shower, and ice water immersion. Physiological responses to brief exposures to heat, cool, and cold. Part II. CirculationKauppinen K. Arctic medical research, 1989.Read the paper ↗PubMed ↗6Source 6 · Clinical trialSome endocrine responses to sauna, shower and ice water immersionKauppinen K, Pajari-Backas M, Volin P, et al.. Arctic medical research, 1989.Read the paper ↗PubMed ↗ A 2026 systematic review of 21 studies found little evidence that contrast therapy changes resting heart rate, blood pressure, vascular health or glucose and lipid metabolism.7Source 7 · Systematic reviewCardiometabolic effects of contrast therapy: A systematic reviewde Haan V, Plasqui G, Pallubinsky H. Experimental Physiology, 2026.Read the paper ↗PubMed ↗